Updated 1:16 p.m. | A poll released today shows Jesse Kelly to be the strongest Republican candidate in the June 12 special election to replace former Rep. Gabrielle Giffords (D-Ariz.).

It is unclear who commissioned the poll of 300 likely general election voters. But it showed that Kelly was the only candidate ahead of former Giffords staffer Ron Barber, the de facto Democratic nominee. Voters go to the polls Tuesday to pick the nominees for the tossup special contest, and Kelly is the odds-on favorite to face Barber in June.

Kelly led Barber 49 percent to 45 percent in a head-to-head matchup. Retired Air Force Col. Martha McSally was tied with Barber at 42 percent. Local college sports TV broadcaster Dave Sitton trailed Barber 39 percent to 43 percent. State Sen. Frank Antenori, who has had financial problems in his campaign, trailed Barber 40 percent to 46 percent.

Pollster Adam Geller of National Research said the polling sample among Republicans was too small to gauge the GOP field against one other. The one-day poll was conducted on April 12.

Kelly ran for Congress in 2010 in a high-profile race against Giffords, and most strategists say his name identification and organization are insurmountable for the other contenders in the brief primary.

The general election that begins on Wednesday is expected to be a hard fought and highly competitive contest, with both parties likely to spend heavily. Barber has generally kept a low profile as the Republicans have waged a generally positive primary. Roll Call rates the special election as a Tossup.

Correction: An earlier version of this post misidentified for whom the poll was conducted.